U.S. patent application number 13/881738 was filed with the patent office on 2013-08-22 for heat recuperation device for an exhaust line.
This patent application is currently assigned to Faurecia Systemes D'Echappement. The applicant listed for this patent is Frederic Greber. Invention is credited to Frederic Greber.
Application Number | 20130213606 13/881738 |
Document ID | / |
Family ID | 44064897 |
Filed Date | 2013-08-22 |
United States Patent
Application |
20130213606 |
Kind Code |
A1 |
Greber; Frederic |
August 22, 2013 |
HEAT RECUPERATION DEVICE FOR AN EXHAUST LINE
Abstract
The heat recuperation device for an exhaust line comprises a
valve body having at least one exhaust gas inlet and at least one
exhaust gas outlet. A shutter element is able to move at least
between a position of blocking off a cutoff section of a path along
which the exhaust gases pass and an uncovering position. The valve
body has an inlet zone situated between the inlet and the cutoff
section, and an outlet zone situated between the cutoff section and
the outlet. The device further comprises a plurality of
heat-exchange tubes, with each tube having an upstream end
connected directly to the inlet zone, a downstream end connected
directly to the outlet zone, and at least one curved portion
between the upstream and downstream ends.
Inventors: |
Greber; Frederic; (Ecot,
FR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Greber; Frederic |
Ecot |
|
FR |
|
|
Assignee: |
Faurecia Systemes
D'Echappement
Nanterre
FR
|
Family ID: |
44064897 |
Appl. No.: |
13/881738 |
Filed: |
October 27, 2011 |
PCT Filed: |
October 27, 2011 |
PCT NO: |
PCT/FR2011/052513 |
371 Date: |
April 26, 2013 |
Current U.S.
Class: |
165/96 |
Current CPC
Class: |
F01N 5/02 20130101; F01N
2240/02 20130101; Y02T 10/12 20130101; F28F 27/02 20130101 |
Class at
Publication: |
165/96 |
International
Class: |
F28F 27/02 20060101
F28F027/02 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 27, 2010 |
FR |
10 58847 |
Claims
1. A heat recuperation device for an exhaust line, comprising: a
valve body having at least one exhaust gas inlet and at least one
exhaust gas outlet, the valve body inwardly defining a direct
passage pathway for exhaust gases from the inlet to the outlet; a
shutter element positioned in the valve body and able to move
relative to the valve body at least between a blocking off position
in which the shutter element blocks off a cutoff section of the
direct passage pathway along which the exhaust gases pass and
thereby prohibits the circulation of the exhaust gases from the
inlet toward the outlet along the direct passage pathway, and an
uncovering position in which the shutter element frees said cutoff
section of the direct passage pathway along which the exhaust gases
pass and thereby allows the circulation of the exhaust gases from
the inlet toward the outlet along the direct passage pathway;
wherein the valve body has an inlet zone situated along the direct
passage pathway between the inlet and the cutoff section, and an
outlet zone situated along the direct passage pathway between the
cutoff section and the outlet; and a plurality of heat exchange
tubes provided for circulation of the exhaust gases, each heat
exchange tube having an upstream end connected directly to the
inlet zone and communicating with the direct passage pathway, a
downstream end connected directly to the outlet zone and
communicating with the direct passage pathway, and at least one
curved portion between the upstream and downstream ends.
2. The device according to claim 1, wherein the shutter element
prohibits the circulation of the exhaust gases in the heat exchange
tubes in the uncovering position.
3. The device according to claim 1, wherein the shutter element
covers the upstream ends the heat exchange tubes or the downstream
ends of the heat exchange tubes the uncovering position.
4. The device according to claim 1, wherein the heat exchange tubes
are U-shaped tubes.
5. The device according to claim 1, wherein each heat exchange
tube, the at least one curved portion covers an angular sector
comprised between 90.degree. and 225.degree..
6. The device according to claim 1, wherein in each heat exchange
tube the upstream and downstream ends extend in a first plane, a
central part of the heat exchange tubes extending in a second plane
that is inclined relative to the first plane, the second plane
preferably forming an angle comprised between 30.degree. and
90.degree. relative to the first plane.
7. The device according to claim 1, wherein the exhaust gases flow
along the inlet and outlet zones in general respective directions,
the upstream and downstream ends of the heat exchange tubes forming
an angle comprised between 45.degree. and 135.degree. with said
respective general directions.
8. The device according to claim 1, wherein the inlet and outlet
zones are situated on a same side wall of the valve body, the
shutter element being rotatably mounted with respect to the valve
body around an axis of rotation situated in an immediate vicinity
of said side wall.
9. The device according to claim 1, including an enclosure having a
coolant inlet, a coolant outlet, and an opening turned toward the
valve body, the heat exchange tubes extending in the enclosure, the
opening being defined by a peripheral edge sealably connected to
the valve body around the inlet and outlet zones.
10. The device according to claim 1, including an enclosure having
a coolant inlet, a coolant outlet, and an opening turned toward the
valve body, and including a wall covering the opening, the wall
being passed through by the heat exchange tubes and not coming into
direct contact with the valve body.
Description
TECHNICAL FIELD
[0001] The invention generally relates to heat recuperation devices
for exhaust lines.
[0002] More specifically, the invention relates to a heat
recuperation device for an exhaust line, comprising: a valve body
having at least one exhaust gas inlet and at least one exhaust gas
outlet, the valve body inwardly defining a direct passage pathway
for the exhaust gases from the inlet to the outlet; a shutter
element positioned in the valve body, able to move relative to the
valve body at least between a blocking off position in which the
shutter blocks off a cutoff section of the path along which the
exhaust gases pass and thereby prohibits the circulation of the
exhaust gases from the inlet toward the outlet along the path, and
an uncovering position, in which the shutter element frees said
cutoff section of the path along which the exhaust gases pass and
thereby allows the circulation of the exhaust gases from the inlet
toward the outlet along the path.
BACKGROUND
[0003] It is known that to ensure the recuperation of part of the
heat from the exhaust gases, two exhaust gas circulation ducts
should be positioned in parallel, with a heat exchanger being
inserted on one of the two ducts, and the other duct making it
possible to bypass the exchanger. A valve including a valve body
and a shutter element, of the type described above, is for example
inserted in each of the two ducts so as to orient the exhaust gases
either toward the exchanger or toward the bypass, as needed.
[0004] Such an assembly is complex, includes a large number of
parts, and is very bulky.
[0005] In this context, the invention aims to propose a heat
recuperation device that is more compact.
SUMMARY
[0006] A heat recuperation device of the aforementioned type
includes a valve body that has an inlet zone situated along a
passage pathway between an inlet and a cutoff section. An outlet
zone is situated along the passage pathway between the cutoff
section and the outlet. The device further comprises a plurality of
heat exchange tubes provided for circulation of the exhaust gases,
with each tube having an upstream end connected directly to the
inlet zone and communicating with the passage pathway, a downstream
end connected directly to the outlet zone and communicating with
the passage pathway, and at least one curved portion between the
upstream and downstream ends.
[0007] The device may also include one or more of the features
below, considered individually according to any technically
possible combinations:
[0008] a shutter prohibits the circulation of the exhaust gases in
the heat exchange tubes in an uncovering position;
[0009] the shutter covers the upstream ends of the heat exchange
tubes or the downstream ends of the heat exchange tubes in the
uncovering position;
[0010] the heat exchange tubes are U-shaped tubes;
[0011] in each heat exchange tube, the curved portion(s) cover an
angular sector comprised between 90.degree. and 225.degree.;
[0012] in each heat exchange tube, the upstream and downstream ends
extend in a first plane, a central part of the heat exchange tubes
extending in a second plane that is inclined relative to the first
plane, the second plane preferably forming an angle comprised
between 30.degree. and 90.degree. relative to the first plane;
[0013] the exhaust gases flow along the inlet and outlet zones in
general respective directions, the upstream and downstream ends of
the heat exchange tubes forming an angle comprised between
45.degree. and 135.degree. with said respective general
directions;
[0014] the inlet and outlet zones are situated on the same side
wall of the valve body, the shutter being rotatably mounted with
respect to the valve body around an axis of rotation situated in
the immediate vicinity of said side wall;
[0015] the device comprises an enclosure having a coolant inlet, a
coolant outlet and an opening turned toward the valve body, the
heat exchange tubes extending in the enclosure, the opening being
defined by a peripheral edge sealably connected to the valve body
around the inlet and outlet zones; and
[0016] the device comprises an enclosure having a coolant inlet, a
coolant outlet and an opening turned toward the valve body, the
device further comprising a wall covering the opening, the wall
being passed through by the heat exchange tubes and not coming into
direct contact with the valve body.
[0017] These and other features may be best understood from the
following drawings and specification.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] Other features and advantages of the invention will emerge
from the detailed description thereof provided below, for
information and non-limitingly, in reference to the appended
Figures, in which:
[0019] FIG. 1 is a perspective view of a heat recuperation device
according to the invention;
[0020] FIG. 2 is a perspective view of the device of FIG. 1,
considered from a different angle, the enclosure of the heat
exchanger not being shown to leave the tubes visible;
[0021] FIG. 3 is a perspective view of the device of FIG. 1, one of
the two half-shells forming the valve body not being shown to leave
the inside of the valve body visible;
[0022] FIG. 4 is a perspective view similar to that of FIG. 3, part
of the enclosure of the heat exchanger not being shown, and the
valve being shown in the blocking off position;
[0023] FIG. 5 is a perspective view of the valve body, similar to
that of FIG. 2, the heat exchange tubes not being shown;
[0024] FIG. 6 is a perspective view of a second embodiment of the
invention, in which the enclosure of the heat exchanger is isolated
from the valve body by an air knife; and
[0025] FIG. 7 is a diagrammatic illustration of the heat exchange
tube according to one alternative embodiment of the invention, in
which the curved central portion of the tube is in a plane that is
inclined relative to the ends of the tube.
DETAILED DESCRIPTION
[0026] The heat recuperation device of FIG. 1 is designed to be
inserted in the exhaust line of a motor vehicle. This device is
designed to recover part of the heat energy from the exhaust gases,
for example to transfer it to the engine coolant, or the passenger
compartment heating circuit.
[0027] The device 1 essentially includes a valve 3 and a heat
exchanger 5.
[0028] The valve 3 includes a valve body 7, an exhaust gas inlet 9,
and an exhaust gas outlet 11. The valve body inwardly defines a
passage pathway 13 for the exhaust gases to pass directly from the
inlet 9 to the outlet 11. A shutter element 15 is positioned inside
the valve body 7, and is able to move relative to the valve body 7
between a blocking off position, in which the shutter element 15
blocks off a cutoff section of the path and thereby prohibits
circulation of the exhaust gases from the inlet 9 to the outlet 11
along the path, and an uncovering position, in which the shutter
element 15 uncovers said cutoff section and thereby allows the
circulation of the exhaust gases from the inlet 9 to the outlet 11
along the path 13.
[0029] The shutter element 15 is able to rotate relative to the
valve body between its blocking off and uncovering positions,
around an axle 17 shown in FIGS. 2, 4 and 5. The axle 17 is mounted
freely rotating on the valve body by guide bearings such as the
bearing 19 shown in FIG. 1. The shutter element 15 is secured to
the axle 17.
[0030] One end 21 of the axle 17 protrudes outside the valve body 7
and is rigidly fixed to a crank 23. The crank 23 is provided to be
connected to an actuator, for example driven by a computer, and
provided to move the valve between its different positions.
[0031] The valve body 7 includes two half-shells 25, 27 alongside
one another by respective edges 29. The edges 29 are alongside one
another, against one another, along a contact plane substantially
parallel to the axle 17. Half of the inlet 9 and the outlet 11 are
each defined by the half-shell 25, and the other half by the
half-shell 27.
[0032] The axle 17 is mounted on the half-shell 27.
[0033] As shown in FIG. 3, the valve 3 also includes a frame 31,
placed inside the valve body 7 and secured to the half-shells 25
and 27. The frame 31 defines a sealing step for the shutter element
15 in the blocking off position thereof. It also defines the cutoff
section. Its entire periphery is pressed against the inner wall of
the valve body 7, and inwardly defines a passage opening for the
exhaust gases that is closed off by the shutter element 15 in its
blocking off position.
[0034] As shown in FIGS. 3 and 5, the valve body 7 bears openings
33 over an exhaust gas inlet zone 35 into the heat exchanger 5. The
valve body 7 has other openings 36 into an exhaust gas outlet zone
37 outside the heat exchanger 5.
[0035] The inlet zone 35 is situated, along the path 13, between
the inlet 9 and the cutoff section defined by the frame 31. The
inlet zone 35 is substantially planar.
[0036] The outlet zone 37 is situated, along the path 13, between
the cutoff section and the outlet 11. The outlet zone 37 is
substantially planar.
[0037] The inlet and outlet zones 35 and 37 are situated on the
same side wall 39 of the valve body 7. They are situated
substantially in the same plane.
[0038] The axle 17 is situated in the immediate vicinity of the
wall 39. More specifically, the side wall 39 has, between the inlet
and outlet zones 35, 37, a zone 41 (FIG. 2) protruding toward the
outside of the valve body 7 relative to the inlet and outlet zones
35 and 37. The zone 41 has a substantially semi-cylindrical shape.
The axle 17 is situated in the immediate vicinity of the protruding
zone 41, such that the axle 17 extends substantially in the plane
of the inlet 35 and outlet 37 zones.
[0039] The number of openings 33 of the inlet zone 35 is equal to
the number of openings 36 of the outlet zone 37.
[0040] The heat exchanger 5 includes a plurality of heat exchange
tubes 43 (FIG. 2) and an outer enclosure 44, the tubes 43 being
placed in the outer enclosure 44.
[0041] Each tube 43 comprises an upstream end 45 directly connected
to the inlet zone 35 of the valve body 7 and communicating with the
passage pathway 13. It also comprises a downstream end 47 directly
connected to the outlet zone 37 and communicating with the passage
pathway 13. It further comprises at least one curved portion 49
between the upstream and downstream ends 45 and 47. The upstream
end 45 of each tube 43 is engaged in one of the inlet openings 33
and is rigidly fixed to the inlet zone 35. It is, for example,
laser welded to the peripheral edge of the opening 33 Likewise, the
downstream end 47 is engaged in one of the outlet holes 36, and is
rigidly fixed to the outlet zone 37. The downstream end 47 is, for
example, laser welded to the peripheral edge of the opening 36.
[0042] In order to make the device 1 more compact, and to bring the
inlet openings 33 as close as possible to the outlet openings 36,
the curved portions 49 each cover an angular sector comprised
between 90.degree. and 225.degree., preferably comprised between
135.degree. and 180.degree..
[0043] In the illustrated example, the tubes 43 are U-shaped tubes.
The upstream and downstream ends 45 and 47 of the same tube 43 are
rectilinear and parallel to each other. They are respectively
substantially perpendicular to the inlet and outlet zones 35 and
37.
[0044] The curved portion 49 is formed by the central portion of
the tube 43 and extends over an angular sector of 180.degree..
[0045] The tubes 43 are, for example, arranged in several layers
superimposed on one another. Each layer, for example, includes four
U-shaped tubes, parallel to each other. The four tubes have
portions curved in a half-circle, with increasing respective radii.
The tube with the smallest radius is situated between the two ends
of the next largest tube, and so forth. Each layer is therefore
substantially planar.
[0046] Preferably, the upstream ends 45 of the heat exchange tubes
43 form, with the general flow direction of the exhaust gases along
the inlet zone 35, an angle comprised between 45.degree. and
135.degree., still more preferably between 60.degree. and
120.degree., and typically equal to 90.degree.. Likewise, the
downstream end 47 of each tube 43 forms, with the general flow
direction of the exhaust gases along the outlet zone 37, an angle
comprised between 45.degree. and 135.degree., preferably comprised
between 60.degree. and 120.degree., and typically equal to
90.degree..
[0047] The enclosure 44 has a coolant inlet 51, a coolant outlet
53, and an unreferenced opening turned toward the valve body 7. The
coolant may, for example, be heat engine coolant, air, or any other
fluid.
[0048] The opening is defined by a peripheral edge that is sealably
connected to the valve body 7 so as to surround the upstream and
downstream zones 35, 37. The peripheral edge is, for example,
alongside the side wall and brazed to that wall.
[0049] The uncovering position of the shutter element 15 is
illustrated in FIG. 3. In that position, the shutter element 15
extends against the downstream zone 37. The circulation of exhaust
gases is prohibited in the heat exchange tubes 43. To that end, the
shutter element 15 blocks off the downstream end 47 of the heat
exchange tubes 43. Alternatively, the shutter element 15 may block
off the upstream ends 45 of the heat exchange tubes.
[0050] The assembly of the heat recuperation device will now be
described.
[0051] The tubes 43 are first mounted on the half-shell 27. They
are welded to the side wall 39 (FIG. 5), for example, by laser
welding or by brazing. The enclosure 44 is then assembled on the
outside of the half-shell 27, and for example brazed thereto. The
shutter element 15, the axle 17 and the guide bearings 19 of the
axle 17 are then assembled on the half-shell 27, and their position
is adjusted such that satisfactory sealing is obtained in the
uncovering position. Next, the guide bearings 19 are rigidly fixed
to the half-shell 27, which guarantees sealed closure of the heat
exchange tubes 43 in the uncovering position of the shutter element
15.
[0052] The frame 31 is then mounted inside the half-shell 27, as
shown in FIG. 3. Its position is adjusted to obtain good sealing
between the frame 31 and the shutter element 15 in the blocking off
position of the shutter element 15. The frame 31 is then rigidly
fixed to the half-shell 27. Lastly, the half-shell 25 is attached
on the half-shell 27 and is, for example, welded thereon.
[0053] The operation of the heat recuperation device is as follows.
When the shutter element 15 is in the uncovering position, the
exhaust gases circulate directly from the inlet 9 to the outlet 11
along the passage pathway 13. The exhaust gases do not circulate in
the heat exchange tubes 43, since the shutter element 15 blocks off
the ends of those tubes.
[0054] On the contrary, when the shutter element 15 is switched
into its blocking off position, the passage pathway 13 is
completely blocked off. However, the two ends of the heat exchange
tubes are free, such that the exhaust gases travel through the heat
exchange tubes 43 and bypass the shutter element 15.
[0055] The exhaust gases cede a significant portion of their heat
energy to the coolant circulating inside the enclosure 44 in
contact with the tubes 43.
[0056] A second embodiment of the invention will now be described,
in reference to FIG. 6. Only the differences between the first and
second embodiments will be outlined below. Identical elements or
elements performing the same function will be designated using the
same references.
[0057] In this second embodiment, the heat exchanger 5 includes, in
addition to the enclosure 44, an additional wall 55 completely
blocking off the opening 57 of the enclosure 44 turned toward the
valve body. The wall 55 is, for example, sealably welded to the
peripheral edge of the opening. The wall 55 has no direct contact
with the side wall 39 of the valve body 7. On the contrary, there
is an interstice in all places, between the wall 55 and the side
wall 39 of the valve body. As shown in FIG. 6, the upstream ends 45
of the heat exchange tubes 43 pass through the wall 55 before
penetrating the inlet openings 33 of the valve body 7. Likewise,
the downstream ends 47 of the heat exchange tubes 43 pass through
the wall 55 before penetrating the outlet openings 36 of the valve
body 7. The tubes 43 therefore pass through the interstice between
the wall 55 and the side wall 39. They are sealably welded to the
wall 55.
[0058] Furthermore, the device includes tabs 59 securing the
enclosure 44 to the valve body 7. For example, a tab 59 secures the
enclosure 44 to a zone of the valve body 7 situated near the inlet
9, and another tab 59 secures the enclosure 44 to a zone of the
valve body 7 situated near the exhaust gas outlet 11. These tabs 59
react the weight of the heat exchanger 5 and transmit it to the
valve body 7. Thus, the stresses created by the weight of the heat
exchanger 5 in the tubes 43 are considerably reduced. The tabs 59
have a significant rigidity in the vertical direction and parallel
to the upstream and downstream ends 45 and 47 of the tubes 43.
However, the tabs 59 have a greater flexibility parallel to the
contact plane between the two half-shells 25, 27, to allow a
differential expansion between the heat exchanger 5 and the valve
3.
[0059] Alternatively, the device does not include tabs 59, the
weight of the heat exchanger 5 being reacted by the tubes 43 and
transmitted to the valve body 7.
[0060] In another alternative not shown, a layer of a thermally
insulating material, for example silica fiber or glass fiber, is
positioned in the interstice between the wall 55 and the side wall
39. The thickness of this layer is for example comprised between 2
and 5 mm.
[0061] In an alternative embodiment shown in FIG. 7, the upstream
and downstream ends 45 and 47 of each heat exchange tube 43 extend
in a first plane, the curved central portion 49 of the tube
extending in a plane that is inclined relative to the first plane.
The second plane forms an angle comprised between 30.degree. and
90.degree. relative to the first plane, preferably comprised
between 30.degree. and 60.degree..
[0062] As shown in FIG. 7, the tube 43 includes three successive
bends. Following the tube 43 from its upstream end 45, the tube 43
first includes a first end 63, then a portion 64 with an
orientation inclined toward the end of the axle 17 across from the
crank 23, and also inclined toward the downstream end 47 of the
tube 43. The second bend is then found, which corresponds to the
curved central portion 49, then a portion 65 oriented toward the
end of the axle 17 bearing the crank 23 and toward the downstream
end 47 of the tube 43, then the third end 66, and lastly the
downstream end 47. The bends 63 and 65 are symmetrical relative to
the median plane of the upstream 45 and downstream 47 ends of the
tube 43.
[0063] Such a shape makes it possible to impart a swirling movement
to the gas that improves the heat exchanges with the coolant. In
fact, as shown in FIG. 7, at the outlet of the first bend 63, the
gas is pressed against the convex side of the tube. At the outlet
of the second bend 49, the gas flows following a swirling movement
when it passes through the third bend 66. The intensity of the
swirling movement will primarily depend on the speed of the gas.
The higher the speed, the more significant the swirling movement
will be. The last bend 66 does not stop the swirling movement.
[0064] In order to still further improve the heat exchanges between
the exhaust gases and the coolant, in an alternative embodiment in
particular illustrated in FIG. 2, it is possible to provide
corrugations 67 in the heat exchange tubes. These corrugations 67
are raised portions formed in the tube, and protruding toward the
inside of the tube so as to increase the turbulence in the flow of
the exhaust gases. The corrugations 67 may assume all types of
shapes. For example, the corrugations 67 assume the form of a
helical raised portion, formed on the tube. The corrugations 67 may
also be formed by a plurality of raised rings distributed along the
tube.
[0065] The tubes 43 may also be provided with disrupting elements.
The disrupting elements are raised portions protruding toward the
inside of the tube, the raised portions, for example, being
substantially periodic. For example, the raised portions are formed
by hammering the outside of the tube.
[0066] The heat recuperation device described above has many
advantages.
[0067] Because the valve body has an inlet zone situated along the
path between the inlet and the cutoff section, and an outlet zone
situated along the path between the cutoff section and the outlet,
the device further comprising a plurality of heat exchange tubes
provided for circulation of the exhaust gases, each tube having an
upstream end directly connected to the inlet zone and communicating
with the passage pathway, the downstream end directly connected to
the outlet zone and communicating with the passage pathway, and at
least one curved portion between the upstream and downstream ends,
the device is particularly compact. The space separating the
upstream and downstream ends of each tube is reduced. It is thus
possible to bring the exhaust gas inlet and outlet closer together
and make the valve body particularly compact as well.
[0068] Furthermore, when the exhaust gases flow directly along the
path between the inlet to the exhaust gas outlet, without going
through the heat exchange tubes, the valve body is relatively
hotter than the exchanger, and hotter than the heat exchange tubes.
Differential expansion thus occurs between the valve and the heat
exchanger. Because the distance between the upstream ends and the
downstream ends of the heat exchange tubes is reduced, this
differential expansion is moderated. It is not necessary to provide
an expansion compensator at the valve or at the heat exchanger.
[0069] Because the shutter element prohibits the circulation of the
exhaust gases in the heat exchange tubes in the uncovering
position, there is no exhaust gas circulation in the exchanger when
the device is in the "bypass" mode, i.e., when the exhaust gases
circulate directly from the inlet toward the outlet of the valve
body. This contributes to limiting heating of the coolant in bypass
mode.
[0070] The fact that the heat exchange tubes are U-shaped gives the
exhaust gases a flow that enables better heat exchanges with the
coolant than if the tubes were straight.
[0071] These heat exchanges are even better if the upstream and
downstream ends of the tubes extend in a first plane and the
central part in a second plane that is inclined relative to the
first.
[0072] Placing the axis of rotation of the shutter member near the
side wall of the valve body to which the ends of the tubes are
fixed makes it possible to arrange the shutter member such that it
can pivot between the position blocking off the path followed by
the exhaust gases and the position blocking off one end of the
tubes. The device is thus simple to design, has a small number of
components, and is light and compact.
[0073] In the embodiments of FIGS. 1 to 5, the device only includes
three half-shell-shaped elements, i.e., the two half-shells making
up the valve body, and the enclosure of the heat exchanger. These
half-shells are typically forged, and their production is a major
investment, in particular to produce the die punches. Minimizing
the number of half-shells makes it possible to reduce the necessary
investment, and allows a certain degree of flexibility in the
design of the device. In fact, the modification of the valve body
or the exchanger will cause a modification on a smaller number of
elements of the device.
[0074] Directly attaching the enclosure of the heat exchanger on
the valve body makes it possible to simplify the structure. On the
contrary, when the heat exchanger has a wall turned toward the
valve body and separated therefrom by an interstice, the heat
isolation between the exchanger and the valve is improved. The
interstice constitutes an air knife thermally isolating the two
elements from one another. The heating of the coolant when the
device is in bypass mode is minimized.
[0075] The heat recuperation device may have multiple
alternatives.
[0076] The valve body may have several exhaust gas inlets and/or
several exhaust gas outlets.
[0077] The shutter member, in the uncovering position thereof, may
not cover the ends of the heat exchange tubes. For example, the
shutter member may be a shutter member of the butterfly type. In
that case, a low residual flow of exhaust gas may occur in the heat
exchange tubes when the shutter member is in the uncovering
position of the path followed by the exhaust gases inside the valve
body.
[0078] The heat exchange tubes are not necessarily U-shaped, but
may assume any type of form. They may each include several curved
portions, connecting straight portions to each other. The upstream
and downstream ends of the tubes are not necessarily parallel to
each other. The ends of the tubes are also not necessarily
perpendicular to the side wall of the valve body bearing the
openings, but may be inclined relative to that wall. The valve body
is not necessarily made up of two half-shells, but may be formed by
a piece or by several tubular portions connected to each other, as
long as it is possible to assemble the valve shutter member inside
the valve body.
[0079] The heat exchange tubes do not necessarily have a circular
section, but may advantageously have an oval section in a so-called
"racetrack" shape. This shape makes it possible to increase the
contact surface between the gases and water for same passage
section offered to the gases inside the tube. Lastly, using such
tubes, as compared to using tubes with a circular section, makes it
possible to decrease the number thereof while maintaining an equal
heat exchange power. This therefore makes it possible to decrease
the number of connections on the half-shell 27. Decreasing the
number of connections makes it possible to reduce the price of the
exchanger part. The gain in terms of connection of the tubes
greatly offsets the price difference between the two tube
technologies. It is thus interesting to use a smaller number of
more expensive, but higher performing tubes to reduce the welding
work on the tubes.
[0080] As described above, using different corrugations increases
the heat exchanges between the exhaust gases and the water, as well
as the back pressure. Furthermore, in each layer of tubes, the
inner tubes, closest to the axle of the valve, have a shorter bend
allowance than the outer tubes, which are further therefrom. Thus,
the back pressure of the inner tubes is weaker than that of the
outer tubes. The flow rate in the outer tubes will be weaker than
in the inner tubes, for an identical exhaust gas passage section.
To rebalance the respective flow rates of the various tubes, very
corrugated tubes should be used inside and weakly corrugated tubes
outside. This is also true if racetrack-type tubes are used.
[0081] Although an embodiment of this invention has been disclosed,
a worker of ordinary skill in this art would recognize that certain
modifications would come within the scope of this disclosure. For
that reason, the following claims should be studied to determine
the true scope and content of this disclosure.
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